This invention relates to systems for automatically electronically distributing information. In particular, the invention is described with respect to a system for distributing securities market information using electronic transmission.
Securities Industry Automation Corporation (SIAC), the assignee of this application, collects and distributes trade and quote data for the U.S. stock and options markets. The data has been distributed using the system depicted in FIG. 1 and is also described in an article entitled xe2x80x9cWall Street Takes Stock of IP Multicastxe2x80x9d by A. Francis Bach published in BUSINESS COMMUNICATIONS REVIEW, January, 1998.
As depicted in FIG. 1 the current system includes two sites from which data is transmitted to provide redundancy and resistance to system failure. One site, xe2x80x9csite Bxe2x80x9d, is located at SIAC""s facility in Brooklyn, N.Y. The other site, xe2x80x9csite Axe2x80x9d, is located at 55 Water Street, New York, N.Y. Site A includes Option Price Reporting Authority (OPRA) system 12, which is a tandem computer which is operated by SIAC to gather and distribute option trade and quote information from all U.S. option exchanges on behalf of the Options Price Reporting Authority consortium. A similar system 16 is provided at site B. Systems 12 and 16 provide redundant capabilities so that if there is a failure of system 12, the tasks normally performed by system 12 will be performed by system 16, and vice versa. In addition to option price reporting, SIAC provides reporting of the stock trading activities on behalf of the Consolidated Tape Association consortium, including a Consolidated Tape System (CTS) which reports trades and a Consolidated Quote System (CQS) which reports quotations. These systems collect, integrate and distribute listed securities"" trade and quote data from the New York Stock Exchange (NYSE), the American Stock Exchange (AMEX), the National Association of Securities Dealers (NASDAQ) and the regional exchanges. Systems 14 and 18 normally provide the CQS service and the CTS service, respectively, but each system has have the capability to assume operations on behalf of the other system in the event of a system failure.
In addition to the redundancy of computers 12, 14, 16, 18, there is provided further redundancy in connection with the distribution of information to the users. In particular each of computers 12, 14, 16 and 18 includes a primary network interface (P) and a backup network interface (B). Each interface is connected to a multicast packet replicator 20 which provides duplicated packet outputs to a local area network through source router 22. One packet is supplied to a distribution router 24A at site A, and the other packet is provided to another distribution packet router 24B at site B via the local area network. Communication of the replicated packets between the sites are provided using an optical cable system.
Distribution routers 24A and 24B at each of the sites distribute identical packet streams called stream A and stream B to users 26 to provide for redundancy in the event of a communications or equipment failure. Further redundancies are built into the system. For example, in the event of a failure in one of the multicast packet replicators 20 or source routers 22, the data stream from any of the systems 12, 14, 16 and 18 can be sent through the backup connection to another multicast packet replica 20 and to an alternate source router. While systems 12 and 16 each have a primary and a backup network port, systems 14 and 18 have a primary, a backup and foldover network ports. In the event of a failure, for example, of system 16 the tasks undertaken by that system would be folded over to system 12 and transmitted using the primary network port of system 12 along with the data normally generated by system 12. The backup ports on systems 12 and 16 are used in the event of a failure of the primary port. In the event of a system failure of system 18, the functions of system 18 would be taken up by system 14 and the data generated would be provided to the network foldover port provided on computer 14 while the primary function and backup ports of computer 14 would continue to provide their normal primary function and provide the backup function for both the primary and foldover network ports. The system as illustrated includes two source routers at each site for providing further redundancy in routing the data stream distributed by each site.
In some instances where subscribers to a data service receive the redundant stream A and stream B data through different receiving ports in a user network, an anomalous behavior can occur which prevents the systems from simultaneously receiving the redundant data streams. Referring to FIG. 2 there is shown a data network of user 26 having two network ports 32 and 36 respectively receiving data stream 30 from site A and data stream 34 from site B. Network ports 32 and 36, are preferably located at Sites A and B respectively. Receiving ports 32 and 36 of system 26 interact with distribution routers 24A and 24B following a Distance Vector Multicast Routing Protocol (DVRP), which in some cases controls the receiving ports 32 and 36 to only receive data stream 30 via receiving port 32. It is an object of the present invention to eliminate such anomalous behavior and provide a system which transmits two data steams, both of which can be received by a user network using the DVMRP protocol
According to the invention there is provided an improvement in a system for electronically distributing data via first and second redundant data distribution facilities, wherein replicating apparatus receives original data packets and provides output first and second data packets for distribution through the first and second data distribution facilities. According to the invention, the replicating apparatus provides the first and second data packets via first and second network interfaces, such that the first and second data packets have different source address data corresponding to the first and second network interfaces.
In a preferred arrangement the first and second data packets are provided via first and second source routers coupled to the first and second network interfaces.
For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description, taken in conjunction with the accompanying drawings, and its scope will be pointed out in the appended claims.